1,720,987 research outputs found
GEO-ELSEvp: a spectral element approach for 2D or 3D dynamic elasto-viscoplastic problems
No full textNear-fault earthquake ground motion prediction by a high-performance spectral element numerical code
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Near-fault earthquake ground motion simulation in the Grenoble Valley by a high-performance spectral element code
No full textNear-fault effects are known to produce specific features of earthquake ground motion, such as long period velocity pulses and directivity, that cannot be predicted by numerical approaches involving vertical plane wave propagation in 1D soil models, used as a standard in engineering applications. Coupling near-fault conditions with site effects induced by complex geological structures, such as deep alluvial basins or steep topographic irregularities, further contributes to the complexity of earthquake ground motion and to the difficulty to provide reliable predictions without making use of large-size 3D numerical simulations. In this paper we present a parametric study of the seismic response of the Grenoble Valley, France, due to a MW 6 seismic source at some 10 km epicentral distance from the urban area, that was carried out in the framework of an international benchmark for earthquake ground motion prediction. The spectral element code GeoELSE for seismic wave propagation analyses in 3D heterogeneous media, in the linear and nonlinear range, was used for this purpose and full advantage was taken of its implementation on parallel computer architectures. After introducing GeoELSE and its parallel performance, and introducing some of its validation benchmarks, the spatial variability of the seismic response of Grenoble valley is quantitatively investigated taking into account two effects: (i) the hypocenter location and (ii) the nonlinear soil behaviour, through a nonlinear visco-elastic soil model. Finally, numerical results are compared with available data and attenuation relationships of peak values of ground motion in the near-fault region. Based on the results of this work, the unfavourable interaction between fault rupture, radiation mechanism and complex geological conditions may give rise to large values of peak ground velocity (exceeding 1 m/s) even in low-to-moderate seismicity areas, and therefore increase considerably the level of seismic risk, especially in highly populated and industrially active regions, such as the Alpine valleys
S2-Project: Near-fault earthquake ground motion simulation in the Sulmona alluvial basin
No full textComment on "Domain Reduction Method for Three-Dimensional Earthquake Modeling in Localized Regions, Part I: Theory," by J. Bielak, K. Loukakis, Y. Hisada, and C. Yoshimura, and "Part II: Verification and Applications," by C. Yoshimura, J. Bielak, Y. Hisada, and A. Fernandez
No full textNonlinear SEM numerical analyses of dry dense sand specimens under rapid and dynamic loading
No full textThe paper mainly concerns the mechanical response of 2D dry dense sand specimens under shock loading.
The problem is numerically analysed by means of a SEM dynamic code, within which an already conceived
non-local viscoplastic constitutive model characterized by a non-associated flow rule and by an anisotropic
strain hardening has been implemented. In particular the strain localization and time dependency of the
material mechanical response are taken into consideration.
Both rapid/static loading and dynamic histories are numerically simulated. In the first case, the time
dependency of the material mechanical response can be captured by neglecting inertial effects, while in the
second one the two factors are superimposed and the propagation of the stress waves within the specimen is
discussed. The interest of these analyses derives from the fact that the diffusion phenomenon takes place
within a specimen already localized
From the seismic source to the structural response: advanced modelling by the spectral element method
No full textExperimental and Numerical Results on Earthquake-Induced Rotational Ground Motions
No full textStimulated by the lack of direct measurements of earthquake-induced ground rotations, a set of experimental and numerical results on rotational ground motion is illustrated. The results cover a relatively broad range of magnitude (4–6.5), and regard both far field and near source conditions.
Experimentally, results are derived through a suitable spatial interpolation procedure of displacement records collected from two dense arrays, Parkway Valley (New Zealand) and UPSAR (California).
Validation checks both with other array-derived methods and with numerical simulations are carried out, to verify the reliability of our estimations and the capability of numerical wave propagation
analysis codes to provide realistic estimates of rotational ground motions over a reasonable frequency band. Peak Ground Velocity (PGV) and Peak Ground Rotation (PGR) values obtained
via the spatial interpolation procedure over dense seismic arrays are then put in comparison with the numerical results computed along two representative cross-sections of the Grenoble Valley (France), in the near field of a MW 6 strike-slip fault. In this case, a combination of topographic, rupture directivity, and site effects produces rotations of remarkable amplitudes, of the order of 10-3 rad.
Finally, PGV-PGR values resulting from both the experimental procedure and the numerical simulations are discussed. A common linear trend between PGV and PGR is found and turns out to be in reasonable agreement with other published results
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